Current drain reduction in ar/vr display systems

ABSTRACT

In some embodiments, eye tracking is used on an AR or VR display system to determine if a user of the display system is blinking or otherwise cannot see. In response, current drain or power usage of a display associated with the display system may be reduced, for example, by dimming or turning off a light source associated with the display, or by configuring a graphics driver to skip a designated number of frames or reduce a refresh rate for a designated period of time.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/448,402, entitled “CURRENT DRAIN REDUCTION IN AR/VR DISPLAY SYSTEMS”,filed Mar. 2, 2017, which claims the benefit of U.S. ProvisionalApplication No. 62/304,098, filed Mar. 4, 2016, which is herebyincorporated by reference in its entirety.

BACKGROUND Field

The present disclosure relates to virtual reality and augmented realityimaging and visualization systems and more particularly to powermanagement in virtual reality and augmented reality systems.

Description of the Related Art

Modern computing and display technologies have facilitated thedevelopment of systems for so called “virtual reality” or “augmentedreality” experiences, wherein digitally reproduced images or portionsthereof are presented to a user in a manner wherein they seem to be, ormay be perceived as, real. A virtual reality, or “VR”, scenariotypically involves presentation of digital or virtual image informationwithout transparency to other actual real-world visual input; anaugmented reality, or “AR”, scenario typically involves presentation ofdigital or virtual image information as an augmentation to visualizationof the actual world around the user.

SUMMARY

The systems, methods and devices of this disclosure each have severalinnovative aspects, no single one of which is solely responsible for thedesirable attributes disclosed herein. A variety of example systems andmethods are provided below.

Embodiment 1: A display system with reduced power use, comprising:

-   -   an inward-facing sensor;    -   a display; and    -   processing electronics in communication with the inward-facing        sensor and the display, the processing electronics configured        to:    -   detect a change in a user's eye status using the inward facing        sensor, and    -   reduce a current drain of the display system based on when the        change in the user's eye status is detected.

Embodiment 2: The display system of Embodiment 1, wherein the change inthe user's eye status is a blink or a saccade.

Embodiment 3: The display system of any of the Embodiments 1-2, whereinthe display comprises a light source, and wherein reducing a currentdrain of the display comprises dimming the light source of the display.

Embodiment 4: The display system of any of the Embodiments 1-2, whereinthe display comprises a light source, and wherein reducing a currentdrain of the display comprises turning off the light source.

Embodiment 5: The display system of any of the Embodiments 1-4, whereinreducing a current drain of the display comprises configuring a graphicsdriver associated with the display to reduce an amount of power consumedby the display.

Embodiment 6: The display system of Embodiment 5, wherein the graphicsdriver is configured to skip a designated number of frames, thedesignated number of frames based upon a length of time that the eyeblinks or saccades.

Embodiment 7: The display system of any of the Embodiments 1-6, whereinthe display comprises an LCD display.

Embodiment 8: The display system of any of the Embodiments 1-7, whereinthe display system comprises an augmented reality or a virtual realitydisplay.

Embodiment 9: The display system of any of the Embodiments 1-8, whereinthe inward-facing sensor comprises a camera.

Embodiment 10: The display system of any of the Embodiments 1-9, whereinthe inward-facing sensor comprises an eye-tracking camera.

Embodiment 11: The display system of any of the Embodiments 1-10,wherein the processing electronics is configured to reduce the currentdrain of the display by reducing a refresh rate associated with thedisplay.

Embodiment 12: The display system of any of the Embodiments 1-11,further comprises a graphics driver wherein reducing the current drainof the display system comprises reducing the power consumption of agraphics driver.

Embodiment 13: A method for reducing power use of a display system,comprising:

-   -   detecting a change in a user's eye status using an inward facing        sensor, and    -   reducing a current drain of the display system based on when the        change in the user's eye status is detected.

Embodiment 14: The method of Embodiment 13, wherein the change in theuser's eye status is a blink or saccade.

Embodiment 15: The method of any of the Embodiments 13-14, wherein thedisplay system comprises a light source, and wherein reducing a currentdrain of the display system comprises dimming the light source of thedisplay system.

Embodiment 16: The method of any of the Embodiments 13-14, wherein thedisplay system comprises a light source, and wherein reducing a currentdrain of the display system comprises shutting off the light source ofthe display.

Embodiment 17: The method of any of the Embodiments 13-16, whereinreducing a current drain of the display system comprises configuring agraphics driver associated with the display system to reduce an amountof power consumed by the display system.

Embodiment 18: The method of Embodiment 17, wherein the graphics driveris configured to skip a designated number of frames, the designatednumber of frames based upon a length of a blink or length of time theeye cannot see.

Embodiment 19: The method of any of Embodiment 17, wherein the graphicsdriver is configured to reduce an amount of power consumed by thedisplay system for a designated period of time, based upon a length of ablink or length of time the eye cannot see.

Embodiment 20: The method of any of the Embodiments 13-19, wherein thedisplay system comprises an LCD display.

Embodiment 21: The method of any of the Embodiments 13-20, wherein thedisplay system comprises an augmented reality or a virtual realitydisplay.

Embodiment 22: The method of any of the Embodiments 13-21, wherein theinward-facing sensor comprises an eye-tracking camera.

Embodiment 23: The method of any of the Embodiments 13-22, whereinreducing the current drain of the display system comprises reducing arefresh rate associated with the display.

Embodiment 24: The method of any of the Embodiments 13-23, whereinreducing the current drain of the display system comprises reducing thepower consumption of a graphics driver.

Embodiment 25: A display system comprising:

-   -   an inward-facing camera;    -   a display; and    -   hardware processing electronics in communication with the        inward-facing camera and the display, the hardware processing        electronics programmed to:    -   using the camera determine when a user of the display is        blinking; and    -   in response to a determination that the user is blinking,        reducing a current drain of the display system.

Embodiment 26: The display system of Embodiment 25, wherein the displaycomprises a light source, and wherein reducing a current drain of thedisplay comprises dimming the light source of the display.

Embodiment 27: The display system of any of the Embodiments 25-26,wherein the light source comprises a backlight.

Embodiment 28: The display system of any of the Embodiments 25-27,wherein reducing a current drain of the display comprises configuring agraphics driver associated with the display to reduce an amount of powerconsumed by the display.

Embodiment 29: The display system of Embodiment 28, wherein the graphicsdriver is configured to skip a designated number of frames, thedesignated number of frames based upon a length of a blink.

Embodiment 30: The display system of Embodiment 28, wherein the graphicsdriver is configured to reduce an amount of power consumed by thedisplay for a designated period of time, based upon a length of a blink.

Embodiment 31: The display system of any of the Embodiments 25-30,wherein the display comprises an LCD display.

Embodiment 32: The display system of any of the Embodiments 25-31,wherein the display comprises an augmented reality or a virtual realitydisplay.

Embodiment 33: A method for reducing current drain in a display,comprising:

-   -   using an inward-facing camera to determine when a user of the        display system is blinking; and    -   in response to a determination that the user is blinking,        reducing a current drain of the display.

Embodiment 34: The method of Embodiment 33, wherein the display comprisea light source, and wherein reducing a current drain of the displaycomprises dimming the light source of the display.

Embodiment 35: The method of Embodiment 34, wherein the light sourcecomprises a backlight.

Embodiment 36: The method of any of the Embodiments 33-35, whereinreducing a current drain of the display comprises configuring a graphicsdriver associated with the display to reduce an amount of power consumedby the display.

Embodiment 37: The method of Embodiment 36, wherein the graphics driveris configured to skip a designated number of frames, the designatednumber of frames based upon a length of a blink.

Embodiment 38: The method of Embodiment 36, wherein the graphics driveris configured to reduce an amount of power consumed by the display for adesignated period of time, based upon a length of a blink.

Embodiment 39: The method of any of the Embodiments 33-38, wherein thedisplay comprises an LCD display.

Embodiment 40: The method of any of the Embodiments 33-39, wherein thedisplay comprises an augmented reality or a virtual reality display.

Embodiment 41: The method of any of the Embodiments 33-40, wherein thecamera comprises an eye-tracking camera.

Embodiment 42: The display system of any of the Embodiments 25-32,wherein the camera comprises an eye-tracking camera.

Embodiment 43: The display system of any of the Embodiments 1-12,wherein the display comprises a head mounted display.

Embodiment 44: The display system of any of the Embodiments 1-12 or 43,further comprising a frame configured to support the display in front ofthe user's eye.

Embodiment 45: The display system of any of the Embodiments 1-12 or43-44, wherein the display system comprises an AR or VR systemconfigured to provide image content to the user with different amountsof divergence, such that the image content appears to the user to belocated at different depths.

Embodiment 46: The method of any of the Embodiments 13-23, wherein thedisplay system comprises a head mounted display.

Embodiment 47: The method of any of the Embodiments 13-23 or 46, whereinthe display system further comprises a frame configured to support thedisplay in front of the user's eye.

Embodiment 48: The method of any of the Embodiments 13-23 or 46-47,wherein the display system comprises an AR or VR system configured toprovide image content to the user with different amounts of divergence,such that the image content appears to the user to be located atdifferent depths.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a user's view of augmented reality (AR) through an ARdevice.

FIG. 2 illustrates an example of wearable display system.

FIG. 3 illustrates a conventional display system for simulatingthree-dimensional imagery for a user.

FIG. 4 illustrates aspects of an approach for simulatingthree-dimensional imagery using multiple depth planes.

FIGS. 5A-5C illustrate relationships between radius of curvature andfocal radius.

FIG. 6 illustrates an example of a waveguide stack for outputting imageinformation to a user.

FIG. 7 illustrates an example of exit beams outputted by a waveguide.

FIG. 8 illustrates a flowchart of a process for reducing current drainof the display system.

It will be appreciated that the drawings are provided to illustrateexample embodiments and are not intended to limit the scope of thedisclosure. Like reference numerals refer to like features throughout.

DETAILED DESCRIPTION Example Display Systems

With reference to FIG. 1, an augmented reality scene 100 is depicted. Itwill be appreciated that modern computing and display technologies havefacilitated the development of systems for so called “virtual reality”or “augmented reality” experiences, wherein digitally reproduced imagesor portions thereof are presented to a user in a manner wherein theyseem to be, or may be perceived as, real. A virtual reality, or “VR”,scenario typically involves presentation of digital or virtual imageinformation without transparency to other actual real-world visualinput; an augmented reality, or “AR”, scenario typically involvespresentation of digital or virtual image information as an augmentationto visualization of the actual world around the user. FIG. 1 shows anexample of such a scene in which a user of an AR technology sees areal-world park-like setting 110 featuring people, trees, buildings inthe background, and a concrete platform 120. In addition to these items,the user of the AR technology also perceives that he “sees” a robotstatue 130 standing upon the real-world platform 120, and a cartoon-likeavatar character 140 flying by which seems to be a personification of abumble bee, even though these elements 130, 150 do not exist in the realworld. Because the human visual perception system is complex, it ischallenging to produce a VR or AR technology that facilitates acomfortable, natural-feeling, rich presentation of virtual imageelements amongst other virtual or real-world imagery elements.

FIG. 2 illustrates an example of wearable display system 200. Thedisplay system 200 includes a display 208, and various mechanical andelectronic modules and systems to support the functioning of thatdisplay 208. The display 208 may be coupled to a frame 212, which iswearable by a display system user or viewer 201 and which is configuredto position the display 208 in front of the eyes of the user 201. Thedisplay 208 may be considered eyewear in some embodiments. In someembodiments, a speaker 216 is coupled to the frame 212 and positionedadjacent the ear canal of the user 201 (in some embodiments, anotherspeaker, not shown, is positioned adjacent the other ear canal of theuser to provide for stereo/shapeable sound control). In someembodiments, the display system may also include one or more microphones(not shown) or other devices to detect sound. In some embodiments, themicrophone is configured to allow the user to provide inputs or commandsto the system 200 (e.g., the selection of voice menu commands, naturallanguage questions, etc.) and/or may allow audio communication withother persons (e.g., with other users of similar display systems).

With continued reference to FIG. 2, the display 208 is operativelycoupled, such as by a wired lead or wireless connectivity, to a localdata processing module 224 which may be mounted in a variety ofconfigurations, such as fixedly attached to the frame 212, fixedlyattached to a helmet or hat worn by the user, embedded in headphones, orotherwise removably attached to the user 201 (e.g., in a backpack-styleconfiguration, in a belt-coupling style configuration). The localprocessing and data module 224 may comprise a hardware processor orprocessing electronics or circuitry, as well as digital memory, such asnon-volatile memory (e.g., flash memory or hard disk drives), both ofwhich may be utilized to assist in the processing, caching, and storageof data. The data include data a) captured from sensors (which may be,e.g., operatively coupled to the frame 212 or otherwise attached to theuser 201), such as image capture devices (such as cameras), microphones,inertial measurement units, accelerometers, compasses, GPS units, radiodevices, and/or gyros; and/or b) acquired and/or processed using remoteprocessing module 228 and/or remote data repository 232, possibly forpassage to the display 208 after such processing or retrieval. The localprocessing and data module 224 may be operatively coupled bycommunication links 236, 240, such as via a wired or wirelesscommunication links, to the remote processing module 228 and remote datarepository 232 such that these remote modules 228, 232 are operativelycoupled to each other and available as resources to the local processingand data module 224. In some embodiments, the local processing and datamodule 224 may include one or more of the image capture devices,microphones, inertial measurement units, accelerometers, compasses, GPSunits, radio devices, and/or gyros. In some other embodiments, one ormore of these sensors may be attached to the frame 212, or may be standalone structures that communicate with the local processing and datamodule 224 by wired or wireless communication pathways.

With continued reference to FIG. 2, in some embodiments, the remoteprocessing module 228 may comprise one or more processors or processingelectronics or circuitry configured to analyze and process data and/orimage information. In some embodiments, the remote data repository 232may comprise a digital data storage facility, which may be availablethrough the internet or other networking configuration in a “cloud”resource configuration. In some embodiments, the remote data repository232 may include one or more remote servers, which provide information,e.g., information for generating augmented reality content, to the localprocessing and data module 224 and/or the remote processing module 228.In some embodiments, all data is stored and all computations areperformed in the local processing and data module, allowing fullyautonomous use from a remote module.

The perception of an image as being “three-dimensional” or “3-D” may beachieved by providing slightly different presentations of the image toeach eye of the viewer. FIG. 3 illustrates a conventional display systemfor simulating three-dimensional imagery for a user. Two distinct images306, 308—one for each eye 302, 304—are outputted to the user. The images306, 308 are spaced from the eyes 302, 304 by a distance 310 along anoptical or z-axis parallel to the line of sight of the viewer. Theimages 306, 308 are flat and the eyes 302, 304 may focus on the imagesby assuming a single accommodated state. Such systems rely on the humanvisual system to combine the images 306, 308 to provide a perception ofdepth for the combined image.

It will be appreciated, however, that the human visual system is morecomplicated and providing a realistic perception of depth is morechallenging. For example, without being limited by theory, it isbelieved that viewers of an object may perceive the object as being“three-dimensional” due to a combination of vergence and accommodation.

Vergence movements (i.e., rolling movements of the pupils toward or awayfrom each other to converge the lines of sight of the eyes to fixateupon an object) of the two eyes relative to each other are closelyassociated with focusing (or “accommodation”) of the lenses of the eyes.Under normal conditions, a change in vergence of the eyes when shiftingattention from one object to another object at a different distance willautomatically cause a matching change in the focus of the lenses of theeyes, or accommodation of the eyes, under a relationship known as the“accommodation-vergence reflex.” Likewise, a change in accommodationwill trigger a matching change in vergence, under normal conditions. Asnoted herein, many stereoscopic or “3-D” display systems display a sceneusing slightly different presentations (and, so, slightly differentimages) to each eye such that a three-dimensional perspective isperceived by the human visual system. Such systems can be uncomfortablefor many viewers, however, since they, among other things, simplyprovide a different presentations of a scene, but with the eyes viewingall the image information at a single accommodated state, and workagainst the “accommodation-vergence reflex.” Display systems thatprovide a better match between accommodation and vergence may form morerealistic and comfortable simulations of three-dimensional imagery.

FIG. 4 illustrates aspects of an approach for simulatingthree-dimensional imagery using multiple depth planes. Objects atvarious distances from eyes 302, 304 on the z-axis are accommodated bythe eyes 302, 304 so that those objects are in focus. The eyes (302 and304) assume particular accommodated states to bring into focus objectsat different distances along the z-axis. Consequently, a particularaccommodated state may be said to be associated with a particular one ofdepth planes 402, which has an associated focal distance, such thatobjects or parts of objects in a particular depth plane are in focuswhen the eye is in the accommodated state for that depth plane. In someembodiments, three-dimensional imagery may be simulated by providingdifferent presentations of an image for each of the eyes 302, 304, andalso by providing different presentations of the image corresponding toeach of the depth planes. While shown as being separate for clarity ofillustration, it will be appreciated that the fields of view of the eyes302, 304 may overlap, for example, as distance along the z-axisincreases. In addition, while shown as flat for ease of illustration, itwill be appreciated that the contours of a depth plane may be curved inphysical space, such that all features in a depth plane are in focuswith the eye in a particular accommodated state.

The distance between an object and the eye 302 or 304 can also changethe amount of divergence of light from that object, as viewed by thateye. FIGS. 5A-5C illustrate relationships between distance and thedivergence of light rays. The distance between the object and the eye302 is represented by, in order of decreasing distance, R1, R2, and R3.As shown in FIGS. 5A-5C, the light rays become more divergent asdistance to the object decreases. As distance increases, the light raysbecome more collimated. Stated another way, it may be said that thelight field produced by a point (the object or a part of the object) hasa spherical wavefront curvature, which is a function of how far away thepoint is from the eye of the user. The curvature increases withdecreasing distance between the object and the eye 302. Consequently, atdifferent depth planes, the degree of divergence of light rays is alsodifferent, with the degree of divergence increasing with decreasingdistance between depth planes and the viewer's eye 302. While only asingle eye 302 is illustrated for clarity of illustration in FIGS. 5A-5Cand other figures herein, it will be appreciated that the discussionsregarding eye 302 may be applied to both eyes 302 and 304 of a viewer.

Without being limited by theory, it is believed that the human eyetypically can interpret a finite number of depth planes to provide depthperception. Consequently, a highly believable simulation of perceiveddepth may be achieved by providing, to the eye, different presentationsof an image corresponding to each of these limited number of depthplanes. The different presentations may be separately focused by theviewer's eyes, thereby helping to provide the user with depth cues basedon the accommodation of the eye required to bring into focus differentimage features for the scene located on different depth plane and/orbased on observing different image features on different depth planesbeing out of focus.

FIG. 6 illustrates an example of a waveguide stack for outputting imageinformation to a user. A display system 600 includes a stack ofwaveguides, or stacked waveguide assembly, 605 that may be utilized toprovide three-dimensional perception to the eye/brain using a pluralityof waveguides 620, 622, 624, 626, 628. In some embodiments, the displaysystem 600 is the system 200 of FIG. 2, with FIG. 6 schematicallyshowing some parts of that system 200 in greater detail. For example,the waveguide assembly 605 may be part of the display 208 of FIG. 2.

With continued reference to FIG. 6, the waveguide assembly 1240 may alsoinclude a plurality of features 630, 632, 634, 636 between thewaveguides. In some embodiments, the features 630, 632, 634, 636 may belenses. The waveguides 620, 622, 624, 626, 628 and/or the plurality oflenses 630, 632, 634, 636 may be configured to send image information tothe eye with various levels of wavefront curvature or light raydivergence. Each waveguide level may be associated with a particulardepth plane and may be configured to output image informationcorresponding to that depth plane. Image injection devices 640, 642,644, 646, 648 may function as a source of light for the waveguides andmay be utilized to inject image information into the waveguides 620,622, 624, 626, 628, each of which may be configured, as describedherein, to distribute incoming light across each respective waveguide,for output toward the eye 302. By using different sources the lightsources themselves act to switch depth planes by switching on or off theillumination for each depth plane, as desired. Light exits an outputsurface 650, 652, 654, 656, 658 of the image injection devices 640, 642,644, 646, 648 and is injected into a corresponding input surface 670,672, 674, 676, 678 of the waveguides 620, 622, 624, 626, 628. In someembodiments, the each of the input surfaces 670, 672, 674, 676, 678 maybe an edge of a corresponding waveguide, or may be part of a majorsurface of the corresponding waveguide (that is, one of the waveguidesurfaces directly facing the world 610 or the viewer's eye 302). In someembodiments, a single beam of light (e.g. a collimated beam) may beinjected into each waveguide to output an entire field of clonedcollimated beams that are directed toward the eye 302 at particularangles (and amounts of divergence) corresponding to the depth planeassociated with a particular waveguide. In some embodiments, a singleone of the image injection devices 640, 642, 644, 646, 648 may beassociated with and inject light into a plurality (e.g., three) of thewaveguides 620, 622, 624, 626, 628.

In some embodiments, the image injection devices 640, 642, 644, 646, 648are discrete displays that each produce image information for injectioninto a corresponding waveguide 620, 622, 624, 626, 628, respectively. Insome embodiments, for example, the image injection devices 640, 642,644, 646, 648 comprise scanning fibers or scanning fiber displaydevices. In some other embodiments, the image injection devices 640,642, 644, 646, 648 are the output ends of a single multiplexed displaywhich may, e.g., pipe image information via one or more optical conduits(such as fiber optic cables) to each of the image injection devices 640,642, 644, 646, 648. It will be appreciated that the image informationprovided by the image injection devices 640, 642, 644, 646, 648 mayinclude light of different wavelengths, or colors (e.g., differentcomponent colors).

In some embodiments, the light injected into the waveguides 620, 622,624, 626, 628 is provided by a light output module 614, which mayinclude a light source, such as backlight 614 b. The backlight 614 b maycomprise one or more emitters such as one or more light-emitting diodes(LEDs). The light from the backlight 614 b may be modified by a lightmodulator 614 a, e.g., a spatial light modulator. The light modulator614 a may be configured to change the perceived intensity of the lightinjected into the waveguides 620, 622, 624, 626, 628. Examples ofspatial light modulators include liquid crystal displays (LCD) and adigital light processing (DLP) displays. In some embodiments, the lightoutput module may include one or more light guides, light pipes orreflectors, which are configured to direct light from the emitter (e.g.,by transmitting and/or reflecting the light) to the light modulator 614a.

A controller 612 controls the operation of one or more of the stackedwaveguide assembly 1240, including operation of the image injectiondevices 640, 642, 644, 646, 648, the light emitter 614 b, and/or thelight modulator 614 a. In some embodiments, the controller 612 is partof the local data processing module 224. The controller 612 includesprogramming (e.g., instructions in a non-transitory medium) thatregulates the timing and provision of image information to thewaveguides 620, 622, 624, 626, 628 according to, e.g., any of thevarious schemes disclosed herein. In some embodiments, the controller612 may be configured to control the operations and/or received inputfrom one or more cameras or sensors (e.g., an inward-facing camera) thatimage an eye of a user, wherein the operation of the light emitter 614 band/or light modulator 614 a may be based at least in part upon imagesof the eye and/or associated image data, such as the determination ofwhen the eye is blinking or moving. In some embodiments, the controllermay be a single integral device, or a distributed system connected bywired or wireless communication channels. The controller 612 may be partof the processing modules or electronics 224 or 228 (FIG. 2) and/orother processing electronics and circuitry in some embodiments.

With continued reference to FIG. 6, the waveguides 620, 622, 624, 626,628, 190 may be configured to propagate light within each respectivewaveguide by total internal reflection (TIR). The waveguides 620, 622,624, 626, 628 may each be planar or have another shape (e.g., curved),with major top and bottom surfaces and edges extending between thosemajor top and bottom surfaces. In the illustrated configuration, thewaveguides 620, 622, 624, 626, 628 may each include outcoupling opticalelements 660, 662, 664, 666, 628 that are configured to extract lightout of a waveguide by redirecting the light propagating within eachrespective waveguide, out of the waveguide to output image informationto the eye 4. Extracted light may also be referred to as outcoupledlight and the outcoupling optical elements may also be referred to lightextracting optical elements. An extracted beam of light may be outputtedby the waveguide at locations at which the light propagating in thewaveguide strikes a light extracting optical element. The outcouplingoptical elements 660, 662, 664, 666, 628 may, for example, be gratings,including diffractive optical features, as discussed further herein.While illustrated as disposed at the bottom major surfaces of thewaveguides 620, 622, 624, 626, 628 for ease of description and drawingclarity, in some embodiments, the outcoupling optical elements 660, 662,664, 666, 628 may be disposed at the top and/or bottom major surfaces,and/or may be disposed directly in the volume of the waveguides 620,622, 624, 626, 628, as discussed further herein. In some embodiments,the outcoupling optical elements 660, 662, 664, 666, 628 may be formedin a layer of material that is attached to a transparent substrate toform the waveguides 620, 622, 624, 626, 628. In some other embodiments,the waveguides 620, 622, 624, 626, 628 may be a monolithic piece ofmaterial and the outcoupling optical elements 660, 662, 664, 666, 628may be formed on a surface and/or in the interior of that piece ofmaterial.

With continued reference to FIG. 6, as discussed herein, each waveguide620, 622, 624, 626, 628 is configured to output light to form an imagecorresponding to a particular depth plane. For example, the waveguide620 nearest the eye may be configured to deliver collimated light, asinjected into such waveguide 620, to the eye 302. The collimated lightmay be representative of the optical infinity focal plane. The nextwaveguide up 622 may be configured to send out collimated light whichpasses through the first lens 630 (e.g., a negative lens) before it canreach the eye 302; such first lens 630 may be configured to create aslight convex wavefront curvature so that the eye/brain interprets lightcoming from that next waveguide up 622 as coming from a first focalplane closer inward toward the eye 302 from optical infinity. Similarly,the third up waveguide 624 passes its output light through both thefirst 630 and second 632 lenses before reaching the eye 302; thecombined optical power of the first 630 and second 632 lenses may beconfigured to create another incremental amount of wavefront curvatureso that the eye/brain interprets light coming from the third waveguide624 as coming from a second focal plane that is even closer inwardtoward the person from optical infinity than was light from the nextwaveguide up 622.

The other waveguide layers 626, 628 and lenses 634, 636 are similarlyconfigured, with the highest waveguide 628 in the stack sending itsoutput through all of the lenses between it and the eye for an aggregatefocal power representative of the closest focal plane to the person. Tocompensate for the stack of lenses 630, 632, 634, 636 whenviewing/interpreting light coming from the world 610 on the other sideof the stacked waveguide assembly 605, a compensating lens layer 638 maybe disposed at the top of the stack to compensate for the aggregatepower of the lens stack 630, 632, 634, 636 below. Such a configurationprovides as many perceived focal planes as there are availablewaveguide/lens pairings. Both the outcoupling optical elements of thewaveguides and the focusing aspects of the lenses may be static (i.e.,not dynamic or electro-active). In some alternative embodiments, eitheror both may be dynamic using electro-active features.

In some embodiments, two or more of the waveguides 620, 622, 624, 626,628 may have the same associated depth plane. For example, multiplewaveguides 620, 622, 624, 626, 628 may be configured to output imagesset to the same depth plane, or multiple subsets of the waveguides 620,622, 624, 626, 628 may be configured to output images set to the sameplurality of depth planes, with one set for each depth plane. This canprovide advantages for forming a tiled image to provide an expandedfield of view at those depth planes.

With continued reference to FIG. 6, the outcoupling optical elements660, 662, 664, 666, 628 may be configured to both redirect light out oftheir respective waveguides and to output this light with theappropriate amount of divergence or collimation for a particular depthplane associated with the waveguide. As a result, waveguides havingdifferent associated depth planes may have different configurations ofoutcoupling optical elements 660, 662, 664, 666, 628, which output lightwith a different amount of divergence depending on the associated depthplane. In some embodiments, the light extracting optical elements 660,662, 664, 666, 628 may be volumetric or surface features, which may beconfigured to output light at specific angles. For example, the lightextracting optical elements 660, 662, 664, 666, 628 may be volumeholograms, surface holograms, and/or diffraction gratings. In someembodiments, the features 630, 632, 634, 636 may not be lenses; rather,they may simply be spacers (e.g., cladding layers and/or structures forforming air gaps).

In some embodiments, the outcoupling optical elements 660, 662, 664,666, 628 are diffractive features that form a diffraction pattern, or“diffractive optical element” (also referred to herein as a “DOE”). Invarious embodiments, the DOE's have a sufficiently low diffractionefficiency so that only a portion of the light of the beam is deflectedaway toward the eye 302 with each intersection of the DOE, while therest continues to move through a waveguide via total internalreflection. The light carrying the image information is thus dividedinto a number of related exit beams that exit the waveguide at amultiplicity of locations and the result is a fairly uniform pattern ofexit emission toward the eye 302 for this particular collimated beambouncing around within a waveguide.

In some embodiments, one or more DOEs may be switchable between “on”states in which they actively diffract, and “off” states in which theydo not significantly diffract. For instance, a switchable DOE maycomprise a layer of polymer dispersed liquid crystal, in whichmicrodroplets comprise a diffraction pattern in a host medium, and therefractive index of the microdroplets can be switched to substantiallymatch the refractive index of the host material (in which case thepattern does not appreciably diffract incident light) or themicrodroplet can be switched to an index that does not match that of thehost medium (in which case the pattern actively diffracts incidentlight).

FIG. 7 shows an example of exit beams outputted by a waveguide. Onewaveguide is illustrated, but it will be appreciated that otherwaveguides in the waveguide assembly 605 may function similarly, wherethe waveguide assembly 605 includes multiple waveguides. Light 700 isinjected into the waveguide 620 at the input surface 670 of thewaveguide 620 and propagates within the waveguide 620 by TIR. At pointswhere the light 700 impinges on the DOE 660, a portion of the lightexits the waveguide as exit beams 702. The exit beams 7 are illustratedas substantially parallel but, as discussed herein, they may also beredirected to propagate to the eye 302 at an angle (e.g., formingdivergent exit beams), depending on the depth plane associated with thewaveguide 620. It will be appreciated that substantially parallel exitbeams may be indicative of a waveguide with outcoupling optical elementsthat outcouple light to form images that appear to be set on a depthplane at a large distance (e.g., optical infinity) from the eye 302.Other waveguides or other sets of outcoupling optical elements mayoutput an exit beam pattern that is more divergent, which would requirethe eye 302 to accommodate to a closer distance to bring it into focuson the retina and would be interpreted by the brain as light from adistance closer to the eye 302 than optical infinity.

Reducing Current Drain

In some embodiments, the display system 600 as discussed above may bepowered by a battery. Current drain reduction or power reduction can bedesirable in order to provide for more run time from the battery or toreduce heating of the device. In some embodiments, current in thedisplay system 200 may be drawn to light the display of the displaysystem 620 (e.g., using the backlight 614 b, image injection devices640, 642, 644, 646, 648 such as possibly one or more scanning fibers orscanning fibers display devices, etc.). In addition, current is employedto control the display (e.g., a graphics processor or driver of thecontroller 612).

As described herein, some current drain reduction or power reduction canbe achieved, for example, by dimming or turning off the display (e.g.,dimming or turning off the display backlight), reducing the displayupdate or refresh rate, or dimming or shutting off the display after atime-out period, based on lack of user interaction.

In some embodiments of augmented reality or virtual reality devices,such as described herein, a camera (or other method) may be used totrack eye movement. The display system 600 may comprise an inward facingcamera 616 directed inward to the face of the user, and in particular,toward the eye of the user (e.g., the eye 302). In some cases, this eyetracking may be done, for example, in order to adjust the view beingdisplayed by the display system 600. For example, the camera 616 may beused to capture images of the eye 302 from which a state or position ofthe eye pupil or iris can be tracked. The state or position of the eyepupil or iris may be used to determine where the user of the device islooking, allowing for the display to be adjusted accordingly.

In some embodiments, eye tracking can be used to determine if the user'seye is in a state where the user is temporarily unable to see. Forexample, the user may not be able to see when the user is blinking. Inaddition, the user may not be able to see when the user's eyes areundergoing a saccade (e.g., a rapid movement of the eyes betweenfixation points).

In some embodiments, the eye tracking camera or inward facing camera (orother sensor or sensor system) can be used to determine if the user isblinking by determining if the pupil or iris of the user is partially orfully blocked from view. For example, the camera may track the iris ofthe user's eye as a dark circle within a background (e.g., the eye whiteof the user). Alternatively, the camera may track the pupil of the useras a darker circle within the iris. When the user is blinking, some orall of the circle defined by the iris or pupil may be obscured or cutoff. The controller 612 may “graphically” detect the blink in responseto the circle pattern corresponding to the user's iris or pupil beingpartially or totally missing. For example, in some embodiments, how muchof the circle pattern is visible may be compared against a thresholdvalue, wherein the user is determined to be blinking if the amount ofvisible (e.g., circle) pattern does not meet the threshold value. Insome embodiments, the threshold value may be preconfigured based uponuser trials.

In some embodiments, the controller 612 may detect whether the user isblinking based upon an amount of contrast calculated from the view ofthe camera 616. For example, a determination may be made as to whetherthe contrast meets a threshold value. In some embodiments, when theuser's eye is open and the iris or pupil of the user is visible, theremay be a high amount of contrast in the images reflected back (e.g.,from the eye or combinations of the eye and eyelid) and captured by thecamera. On the other hand, when the user's eye is closed (e.g., theuser's eyelid covers the eye), the amount of contrast may be much lowercompared to when the user's eye is open (e.g., at least partially open).As such, the controller 612 may detect a blink when the contrast islower than the threshold value.

In some embodiments, if the controller 612 is unable to detect aposition of the iris or pupil of the user. For example, the controller612 may generate an “error” state if the iris or pupil of the user isunable to be detected, which may also serve as a blink detection.

In some embodiments, the controller 612 may detect a saccade by theuser. When the user's eyes are in a state of saccade, the user may notperceive any visual information despite the user's eyes being open. Insome embodiments, the controller 612 may detect a saccade by using theinward facing camera 616 to track a location of the user's iris or pupil(e.g., as a dark circle, as discussed above). If movement of the user'siris or pupil above a certain rate is detected, then the user may beconsidered to be in a saccade state.

In some embodiments, a time period of a blink or saccade may be apredetermined period of time. The predetermined period of time may bedetermined based upon empirical data from user studies. In someembodiments, a time period for a blink or saccade may be measured by oneor more sensors of the display system 600 (e.g., the inward facingcamera 616) based upon eye open/closed criteria or eye movement criteriaas discussed above. If the eye is closed or experiencing saccades for aperiod of time, the system may be set to a lower energy state toconserve power.

Although the above discussion refers primarily to using a camera todetermine a state where the user is unable to see (e.g., due to a blinkor saccade), any type of hardware that can be used to detect a state ofthe user's eye may be used, such as other types of sensor systems. Insome cases, it may be desirable to utilize hardware already integratedwith display system 600 (e.g., hardware designed to serve other purposesin the display system 600), in order to reduce power consumption thatwould be consumed by the addition of new hardware. The camera or othertype of sensor system is not limited to using visible light and mayemploy infrared (IR) light.

In some embodiments, the display system 600 may reduce its current orpower drain during the period when the user is unable to see (e.g., dueto a blink or saccade). For example, current drain or power usage of thedisplay can be reduced by employing one or more current drain or powerreduction techniques, which may include dimming or turning off a lightsource for the display (e.g., a backlight) associated with the display.In some embodiments, the light source (e.g., backlight) 614 b of thedisplay system 600 may be dimmed or turned off. In other embodiments(e.g., display systems using OLED displays that do not have abacklight), current drain or power usage may be reduced by dimming orturning off one or more active pixels of the display. Other types ofdisplay components or displays may be turned off, dimmed or set to alower power consumption mode when the eye cannot see (e.g., during ablink or saccades).

In alternative or combination, a graphics driver or processor orprocessing electronics associated with the display “skips” a number offrames or waits for a designated period of time where the graphicsdriver is in a state that causes less power to be consumed than ifproviding new images or refreshing images. For example, the graphicsdriver can cause the graphics processor to suspend refreshing adisplayed image, or reduce a refresh rate of the display, thus consumingless power in comparison to normal operation. In some implementations,the number of frames or period of time during which current drain isreduced may be configured to correspond to a length of the blink orsaccade. The time period for a blink, for example, is typically between100 to 400 mSec.

It is understood that any of the current drain reduction techniquesdiscussed herein may be performed independently or in combination witheach other. For example, in some embodiments, in response to thedetection of a blink or saccade, the controller 612 may dim thebacklight 614 b as well as cause the graphics drive to skip a designatednumber of frames. In other embodiments, the controller 612 may cause thegraphics driver to skip a designated number of frames without dimmingthe backlight 614 b, or vice versa.

FIG. 8 illustrates a flowchart of an example process for reducingcurrent draining or power usage, in accordance with some embodiments.Any portion of this flowchart may be executed by electronics such asprocessing electronics or circuitry. At block 802, a determination ismade as to whether a state when a user of the display system is unableto see is detected (e.g., a blink or saccade by the user). In someembodiments, this may be done using an eye tracking or inward facingcamera or other sensor or sensor system that determines whether thepupil or iris of the user is blocked from view or is experiencing rapidmovement. If a blink or saccade is detected, the process may proceed toblock 804. Otherwise, the process may continue to monitor the eye, forexample, to detect for a blink or saccade by the user of the displaysystem.

At block 804, a light source associated with the display is dimmed orturned off. For example, the light source may be configured to enter alow power mode or be disabled. In some embodiments, the light source maycomprise the backlight 614 b. In other embodiments, the light source maycomprise a plurality of active pixels of the display (e.g., of an OLEDdisplay). Other light sources and display configurations are possible.

At block 806, a graphics driver associated with the display system mayreduce an amount of power consumed. For example, the graphics driver mayskip X number of frames or wait for a period of time Y, wherein X and Yare determined based upon a period of a blink (e.g., between 100 and 400mSec) or saccade. In some embodiments, the graphics driver may reduce arefresh rate of the display.

At block 808, the light source associated with the display (e.g., thebacklight 614 b, active pixels of the display, and/or the like) or othercomponents of the display is turned back on or un-dimmed, and thedisplay system resumes normal operation. It is understood that theprocess illustrated in this flowchart is an example, and that steps maybe excluded, added, and/or reordered.

It is understood that although FIG. 8 illustrates both dimming/turningoff a light source associated with the display (blocks 804, 808) andreducing a power consumption of a graphics driver or processor (block806), in other embodiments, the display system 600 may perform anycombination of current drain or power reduction techniques. For example,in some embodiments, the display system 600 may perform onlydimming/turning off the light source of the display, only reducing apower consumption of the graphics driver or processor (e.g., skippingframes, reducing a refresh rate, and/or the like), or both. Powerconservation can also come from other components. For example, settingthe spatial light modulator or one or more scanning fibers or scanningfiber display devices to a lower power state can also reduce powerconsumption.

The average person blinks about once every 2 to 10 seconds, for a periodof 100 to 400 msec. Thus, in a less frequent scenario, the eyes areclosed for about 1% of the time. For a more typical scenario, the eyeswill be closed for 2% to 5% of the time. Therefore a reduction of a fewpercent can possibly be achieved in the current drain associated withlighting the display using a light source (e.g., a backlight or activepixels) and/or the graphics driver/processor.

Various example embodiments of the invention are described herein.Reference is made to these examples in a non-limiting sense. They areprovided to illustrate more broadly applicable aspects of the invention.Various changes may be made to the invention described and equivalentsmay be substituted without departing from the spirit and scope of theinvention. For example, while advantageously utilized with AR displaysthat provide images across multiple depth planes, the augmented realitycontent disclosed herein may also be displayed by systems that provideimages on a single depth plane.

Many modifications may be made to adapt a particular situation,material, composition of matter, process, process act(s) or step(s) tothe objective(s), spirit or scope of the present invention. Further, aswill be appreciated by those with skill in the art that each of theindividual variations described and illustrated herein has discretecomponents and features which may be readily separated from or combinedwith the features of any of the other several embodiments withoutdeparting from the scope or spirit of the present inventions. All suchmodifications are intended to be within the scope of claims associatedwith this disclosure.

The invention includes methods that may be performed using the subjectdevices. The methods may comprise the act of providing such a suitabledevice. Such provision may be performed by the user. In other words, the“providing” act merely requires the user obtain, access, approach,position, set-up, activate, power-up or otherwise act to provide therequisite device in the subject method. Methods recited herein may becarried out in any order of the recited events that is logicallypossible, as well as in the recited order of events.

Example aspects of the invention, together with details regardingmaterial selection and manufacture have been set forth above. As forother details of the present invention, these may be appreciated inconnection with patents and publications generally known or appreciatedby those with skill in the art. The same may hold true with respect tomethod-based aspects of the invention in terms of additional acts ascommonly or logically employed.

In addition, though the invention has been described in reference toseveral examples optionally incorporating various features, theinvention is not to be limited to that which is described or indicatedas contemplated with respect to each variation of the invention. Variouschanges may be made to the invention described and equivalents (whetherrecited herein or not included for the sake of some brevity) may besubstituted without departing from the spirit and scope of theinvention. In addition, where a range of values is provided, it isunderstood that every intervening value, between the upper and lowerlimit of that range and any other stated or intervening value in thatstated range, is encompassed within the invention.

Also, it is contemplated that any optional feature of the inventivevariations described may be set forth and claimed independently, or incombination with any one or more of the features described herein.Reference to a singular item, includes the possibility that there areplural of the same items present. More specifically, as used herein andin claims associated hereto, the singular forms “a,” “an,” “said,” and“the” include plural referents unless the specifically stated otherwise.In other words, use of the articles allow for “at least one” of thesubject item in the description above as well as claims associated withthis disclosure. It is further noted that such claims may be drafted toexclude any optional element. As such, this statement is intended toserve as antecedent basis for use of such exclusive terminology as“solely,” “only” and the like in connection with the recitation of claimelements, or use of a “negative” limitation.

Without the use of such exclusive terminology, the term “comprising” inclaims associated with this disclosure shall allow for the inclusion ofany additional element—irrespective of whether a given number ofelements are enumerated in such claims, or the addition of a featurecould be regarded as transforming the nature of an element set forth insuch claims. Except as specifically defined herein, all technical andscientific terms used herein are to be given as broad a commonlyunderstood meaning as possible while maintaining claim validity.

The breadth of the present invention is not to be limited to theexamples provided and/or the subject specification, but rather only bythe scope of claim language associated with this disclosure.

What is claimed is:
 1. A display system with reduced power use,comprising: an inward-facing sensor; a display comprising a lightsource, wherein the display system comprises an AR or VR systemconfigured to provide image content to the user with different amountsof divergence, such that the image content appears to the user to belocated at different depths; and processing electronics in communicationwith the inward-facing sensor and the display, the processingelectronics configured to: detect a first change in a user's eye statususing the inward-facing sensor, the first change comprising anindication associated with a closed state of the user's eyes, detect asecond change in a user's eye status, the second change comprising anindication associated with an open state of the user's eyes, reduce acurrent drain of the display system in response to detecting the firstchange in the user's eye status, wherein reducing the current drain ofthe display comprises dimming the light source of the display withoutturning off the light source, and increase a current drain of thedisplay system in response to the detected second change in the user'seye status.
 2. The display system of claim 1, wherein the first andsecond changes in the user's eye status corresponds to a blink.
 3. Thedisplay system of claim 1, wherein reducing the current drain of thedisplay further comprises configuring a graphics driver associated withthe display to reduce an amount of power consumed by the display.
 4. Thedisplay system of claim 3, wherein the graphics driver is furtherconfigured to skip a designated number of frames, the designated numberof frames based upon a length of time that the user is unable to see. 5.The display system of claim 1, wherein the display comprises a liquidcrystal display (LCD).
 6. The display system of claim 1, wherein theinward-facing sensor comprises a camera.
 7. The display system of claim1, wherein the processing electronics is further configured to reducethe current drain of the display by reducing a refresh rate associatedwith the display.
 8. The display system of claim 1, further comprises agraphics driver wherein reducing the current drain of the display systemfurther comprises reducing the power consumption of the graphics driver.9. The display system of claim 1, wherein the display system comprises ahead-mounted display configured to be worn by a user and disposed on aframe configured to support said display thereon, said displayconfigured to project light into said user's eye to display augmentedreality image content to the user's vision field, at least a portion ofsaid display being transparent and disposed at a location in front ofthe user's eye when the user wears the frame such that said transparentportion transmits light from a portion of an environment in front of theuser and said head-mounted display to the user's eye to provide a viewof said portion of the environment in front of the user and saidhead-mounted display.
 10. The display system of claim 1, wherein theuser is unable to see between the first and second changes.
 11. A methodfor reducing power use of a display system, comprising: detecting afirst change in a user's eye status using an inward-facing sensor, thefirst change comprising an indication associated with a closed state ofthe user's eyes, detecting a second change in a user's eye status, thesecond change comprising an indication associated with an open state ofthe user's eyes, reducing a current drain of the display system inresponse to detecting the first change in the user's eye status, whereinreducing the current drain of the display comprises dimming a lightsource of the display without turning off the light source, andincreasing a current drain of the display system in response todetecting the second change in the user's eye status, wherein thedisplay system comprises an AR or VR system configured to provide imagecontent to the user with different amounts of divergence, such that theimage content appears to the user to be located at different depths. 12.The method of claim 11, wherein the first and second changes in theuser's eye status corresponds to a blink.
 13. The method of claim 11,wherein reducing the current drain of the display system furthercomprises configuring a graphics driver associated with the displaysystem to reduce an amount of power consumed by the display system. 14.The method of claim 13, further comprising skipping a designated numberof frames, the designated number of frames based upon when the user isunable to see.
 15. The method of claim 11, further comprising reducingan amount of power consumed by the display system for a designatedperiod of time, based upon a length of a blink.
 16. The method of claim11, wherein the display system comprises a liquid crystal display (LCD).17. The method of claim 11, wherein reducing the current drain of thedisplay system further comprises reducing a refresh rate associated withthe display.
 18. The method of claim 11, wherein reducing the currentdrain of the display system further comprises reducing the powerconsumption of a graphics driver.
 19. The method of claim 11, whereinthe display system comprises a head-mounted display configured to beworn by a user and disposed on a frame configured to support saiddisplay thereon, said display configured to project light into saiduser's eye to display augmented reality image content to the user'svision field, at least a portion of said display being transparent anddisposed at a location in front of the user's eye when the user wearsthe frame such that said transparent portion transmits light from aportion of an environment in front of the user and said head-mounteddisplay to the user's eye to provide a view of said portion of theenvironment in front of the user and said head-mounted display.